Due to laws requiring the reduction of the levels of hydrocarbons that vehicles may emit into the atmosphere, it is necessary for automotive designers to include systems in vehicles to measure and control emissions. Hydrocarbons are released in a vehicle's exhaust, as well as from the engine, even when the engine is not operating. These emissions leak out of the vehicle from many sources, including an air induction system.
Many methods have been utilized to measure the level of hydrocarbons in the exhaust. For example, the hydrocarbon level in vehicle exhaust gas is measured by placing a hydrocarbon adsorbing material in the exhaust stream of the vehicle. The hydrocarbon adsorbing material is connected to a sensor. The sensor is connected to an on-board diagnostic system that monitors the exhaust emissions and notifies an operator of the vehicle when the hydrocarbon level exceeds a certain level. However, this method does not significantly reduce the hydrocarbon emissions.
One method of reducing the levels of hydrocarbon emissions is to adsorb or trap hydrocarbons with the use of a filter-like device. Typically, the hydrocarbon-trapping device is formed of monolith carbon that is disposed in the air induction system of motor vehicles. One of the problems with such positioning of the hydrocarbon-trapping device in the air induction system is the risk of breakage due to vibration or throttle engine backfire. In addition to the loss of function of the hydrocarbon-trapping device, large pieces of carbon monolith can be drawn into the engine, which can cause undesirable damage. A further problem can arise if the adsorbing element becomes saturated with hydrocarbons, which can significantly reduce the efficiency.
It would be desirable to produce a hydrocarbon-trapping device that maximizes hydrocarbon adsorption, wherein a positioning and design of the device militates against damage to the device and facilitates access to the device for replacement.